Cross sections on the rise   Robert Leverett
  Dec 21, 2005 13:09 PST 

Will, Jess, Don, Lee, John, Ed, et all:

    From my 4th floor office window on the Mercy Medical Center Campus
in Springfield, MA, I can look directly across to a gorgeous pin oak
tree that is 80 yards away. It is 90.4 feet tall, has a CBH of 12.1
feet, branches at 23 feet above its base, and has a maximum lateral
crown spread of an impressive 104 feet as determined from a distance. I
suspect that the actual is between 95 and 100 feet. I'll confirm that
tomorrow.

     A level gaze from my chair brings me to 45 feet or half way up the
tree - a perfect vertical vantage point. I can clearly see the spread of
limbs in the morning (the tree is to my west) and I can count most of
them since foliage no longer obscures vision. I think I can see the
limbs through an arc of about 330 degrees. I'll inspect the remaining
30%, or whatever it turns out to be, from the ground.

   A novel thought occurred to me this morning. With the RD 1000 I could
model the tree pretty thoroughly from my office, excepting limbs in the
hidden 30%. I could calculate the total cross-sectional area of wood at
different heights as a kind of profile. Staying with cross-sectional
area at different heights would free me from trying to calculate limb
lengths. Of course, the cross-sections wouldn't provide the whole
picture and wouldn't yield volume, but the exercise would be
interesting.

   So I plan to arrive at my office early tomorrow AM and spend about an
hour taking measurements of the limbs at 45 foot level with the RD 1000,
using its magnifier. If I'm successful tomorrow, on Friday, I'll drop to
30 feet and do another cross-section. Next week, I'll do one at 60 feet.
I'll then model from 0 to 23 feet. No problems there. The section
between 23 and 30 feet is the confusing area where the limbs begin to
emerge until their separation is visibly distinct from my vantage point.
I'll save that section for last. Any suggestions?

   Lee, did you do anything like this when you analyzed crown area in
your studies in the Porkies?

Bob


Robert T. Leverett
Cofounder, Eastern Native Tree Society
RE: Cross sections on the rise   Robert Leverett
  Dec 22, 2005 06:12 PST 

Ed,

Yes, I'm unquestionably obsessed. Last night Will Blozan and I
discussed the idea of computing the cross-sectional area of trunk and
limbs at different heights. Will likes the idea. It is another way to
assess how much wood exists at different heights. So we visualize the
tree cut by horizontal planes at a set of chose heights and calculating
the area of the wood that intersects each plane. Near the base of the
tree it is all trunk. Then perhaps a split trunk, and then trunk and
limbs or all limbs.

More later.

Bob
Re: Cross sections on the rise   Lee E. Frelich
  Dec 22, 2005 11:25 PST 

Bob:

No, I didn't do wood cross sectional area at different levels, and I
haven't seen any such analyses before--so your analysis will be
unique. What we did do, is cross sectional area of the crown at different
levels, to calculate the amount of space the tree occupies, so that we
could get the relative amount of area and volume each species occupied in
the forest.

 The oak tree I am going to see next time I visit Sweden
is thought to be 1000 years old, and has appeared in various
historical records for at least 600 years. It has a CBH of 45 feet, and
DBH of 14 feet. 

Lee
Re: Cross sections on the rise   Jess Riddle
  Dec 22, 2005 17:33 PST 

Hi Bob,

Your exploration of total cross-sectional area at various heights
sounds intriguing. I remember Will Blozan mentioning the idea to me a
several months ago, and I immediately thought the idea fascinating
although I couldn't see any direct applications. I'm looking forward
to reading about your results, and what conclusions you come to
through your exploration.

Jess Riddle
First look   Robert Leverett
  Dec 23, 2005 07:18 PST 
Jess, Will, et al:

    The idea for computing the cross-sectional area, which I'll here
after refer to as CSA was in part an attempt to concentrate on what I
could measure easiest. I was very pleased when Will told me he had been
thinking about it. Handling complex limb structures requiring modeling
of 15 to 20 main limbs and perhaps as many secondary branches is a
daunting job. To do it justice, limb modeling must await the new
instrument, i.e. the reticled microscope-telescope. The Rd 1000 is just
not accurate enough to handle complex limb structures.

    Passing several horizontal planes through the tree and calculating
the CSA of wood that emerges through each plane would give a
3-dimensional view of the tree's architecture that might prove highly
valuable to characterizing differences among species and how the young
trees of a species differ from the old growth forms. Well, so much for
my justifications.

    My first crack at the pin oak visible from my window has yielded
some crude measures. They are summarized in the table below.

Hgt = 90 CBH=11.8
Max Spread = 97
Hgt-ft No Trunks/limbs CSA-ft^2 % of Hgt % of 2.5-CSA
2.5 1 12.57 3% 100%
4.5 1 11.09 5% 88%
48 12 8.34 53% 66%
65 7 1.67 72% 13%
90 0 0 100% 0%
   

     As time goes on, I'll refine them and we'll see how the numbers
change with the refinements. For example, I measured the tree with my
D-tape this morning. It's 11.8-foot CBH (45.1" DBH) is at variance with
what I got with the RD 1000 with magnifier which could be read as either
46.7 or 47.4. Had I not measured the tree with the D-tape, I would have
chosen 47.4". So it appears that the magnifier produces high numbers on
large diameters at long distances. This is what I first discovered in
early tests with the magnifier. The absolute magnitude of the error does
not carry over to small diameters. Otherwise most of my limb
measurements would disappear. Now you see them, subtract a 1.3"
correction factor, and now you don't.

Bob



Robert T. Leverett
Cofounder, Eastern Native Tree Society
RE: What Difference Seven Years?   Robert Leverett
  Dec 27, 2005 12:51 PST 
Ed,

    BTW, implementing the horizontal slice concept to profile the
cross-sectional amount of wood in a tree at different heights is
presenting some challenges. From a single vantage point, locating the
spot on different trunks/limbs/branches that are at the same height
requires a lookup table and some experimentation. I will soon send you
and others an Excel table showing my approach and soliciting ideas for
improvement.

Bob
RE: Cross sections on the rise   Roman Dial
  Dec 28, 2005 02:48 PST 

Jess and Bob,

One application of cross sectional area by height would be the
computation of leaf area index by height, giving a vertical profile of
foliage density.

Roman
RE: Cross sections on the rise    Robert Leverett
   Dec 28, 2005 07:00 PST 

Roman,

   Does this suggest that the foliage density could be predicted by the
cross-sectional area of the wood at any specified height - perhaps with
an offset? This would seem to be the case high in the canopy, but it
wouldn't apply at lower heights. Would you shoot for the middle of the
canopy to apply the technique?

   From a practical standpoint, the amount of work needed to identify
the spots on many limbs that are at a prescribed vertical height above
base is daunting. The features of the RD 1000 that allow one to quickly
scan up a particular height applies only along the vertical line which
has at its horizontal distance, the value set into the RD 1000. There is
no way to quickly compensate as one moves from limb to limb unless
shooting at eye level. One can alternately shoot sufficiently low and
high on the limb to encompass the point that is at the prescribed
height. One can gradually zero in on the spot, but it isn't just a point
and shoot proposition. So computing the cross-sectional area of wood at
a prescribed height must remain a labor intensive job. Oh well.

   One long term use of this kind of measuring might be to develop
characteristic profiles for different species in open and closed growing
environments. I don't know. At this point, I'm more concerned with just
developing the measuring technology and leaving it up to the Lee
Frelichs, Bob Van Pelts, Roman Dials, Tom Diggins, Don Braggs, etc. to
figure out how to make good scientific use of the data.

Bob    
RE: Cross sections on the rise    Robert Leverett
   Dec 28, 2005 07:00 PST 

Roman,

   Does this suggest that the foliage density could be predicted by the
cross-sectional area of the wood at any specified height - perhaps with
an offset? This would seem to be the case high in the canopy, but it
wouldn't apply at lower heights. Would you shoot for the middle of the
canopy to apply the technique?

   From a practical standpoint, the amount of work needed to identify
the spots on many limbs that are at a prescribed vertical height above
base is daunting. The features of the RD 1000 that allow one to quickly
scan up a particular height applies only along the vertical line which
has at its horizontal distance, the value set into the RD 1000. There is
no way to quickly compensate as one moves from limb to limb unless
shooting at eye level. One can alternately shoot sufficiently low and
high on the limb to encompass the point that is at the prescribed
height. One can gradually zero in on the spot, but it isn't just a point
and shoot proposition. So computing the cross-sectional area of wood at
a prescribed height must remain a labor intensive job. Oh well.

   One long term use of this kind of measuring might be to develop
characteristic profiles for different species in open and closed growing
environments. I don't know. At this point, I'm more concerned with just
developing the measuring technology and leaving it up to the Lee
Frelichs, Bob Van Pelts, Roman Dials, Tom Diggins, Don Braggs, etc. to
figure out how to make good scientific use of the data.

Bob